严格来说,该短语的完整结构是"prevent sb./sth. from doing sth."(注意:"prevent"是及物动词,后面必须接宾语,不能直接说"prevent from doing"),意为:
主语(实施阻止动作的人/物)+ prevent + 宾语(被阻止的人/物)+ from + 动名词(被阻止的动作)
"from"的省略:在主动语态中,"from"可以省略(但省略后语气更简洁,含义不变);
但在被动语态中,"from"不能省略(否则会改变句意)。
动名词的使用:"from"是介词,后面必须接动名词(doing),不能接动词原形。
The heavy snow prevented us from going to school.(大雪阻止了我们去上学。)
The teacher prevented the students (from) talking in class.(老师阻止学生在课堂上说话。)
We were prevented from going to school by the heavy snow.(我们被大雪阻止去上学。)
The students were prevented from talking in class by the teacher.(学生被老师阻止在课堂上说话。)
The fence prevents animals from entering the garden.(围栏阻止动物进入花园。)
The password prevents strangers from accessing your account.(密码阻止陌生人访问你的账户。)
与"stop from doing" "keep from doing"的区别:
prevent/stop sb. from doing:主动语态中"from"可省,强调"成功阻止";
keep sb. from doing:"from"不能省略(省略后变为"keep sb. doing",意为"让某人一直做",完全相反),强调"持续阻止"。
总结:"prevent sb./sth. from doing sth."是表达"阻止某人/物做某事"的常用结构,重点是记清"及物动词+宾语+from+动名词"的搭配,以及"from"在被动语态中不可省的规则。